Résume | Given a complex number w, Im w>0, and an analytic circle diffeomorphism f, one can construct a torus by glueing an annulus (0< Im z < Im w) in C/Z by the action of f+w. The modulus of this torus is called the complex rotation number of f+w. Limit values of the complex rotation number (as Im w tends to zero) form a fractal set ``Bubbles'', related to the dynamics of a circle diffeomorphism f. I will discuss this relation, as well as shapes of bubbles and their self-similarity. |